Model 1: Rabbits, Grass, Weeds
1.    The model’s default settings are such that at first the weeds are not present (weeds-grow-rate = 0, weeds-energy = 0).  This is so

that you can look at the interaction of just rabbits and grass. Once you have done this, you can start to add in the effect of weeds.
2.    Run the simulation with default settings, and slow down the simulation speed. Describe what happens to the size of the rabbit

population over time.
3.    Does there seem to be a relationship between the size of the rabbit population and the grass population? What is the relationship?
4.    Now add weeds by making the sliders WEEDS-GROW-RATE the same as GRASS-GROW-RATE and WEEDS-ENERGY the same as GRASS-ENERGY. How do

the grass and weed populations compare? How does the grass population compare to the previous run without weeds?
5.    Did this affect the rabbit population size compared to when there was no weeds? If so, how?
6.    What if the weeds grow at the same rate as grass, but they give less energy to the rabbits when eaten (WEEDS-ENERGY is less than

GRASS-ENERGY)?  What effect does that have on the relative size of the rabbit population compared to previous settings?
7.    Play with the “birth threshold” for rabbits. Describe what happens to the rabbit and grass populations when you lower the

threshold.
8.    Increase the energy provided by grass and by weeds (set birth threshold back to default value of 15). Describe what happens to the

rabbit, grass, and weed populations now.
9.    What if the weeds grow more quickly than grass?  What effect does that have on the relative size of the grass and weed populations

compared to previous settings?  Does it affect the rabbit population?
10.    This model allows you to explore a three species community.  As you change growth rates and energy content of the plants, rabbit

population size and energy requirement for reproduction you will observe how the three species’ interactions affect the community.  Using

your findings as evidence, write a paragraph that summarizes this predator-prey system.
Model 2: Wolf Sheep Predation
1.    Run a few trials. What happens to the population size of the sheep and wolves in the first few “ticks” of a trial using default

values?
2.    What happens in successive runs of the simulation? Is the behavior of this system predictable? Why or why not?
3.    Try different values for the “initial-number-wolves”. What happens to the size of the sheep and wolf populations? Is this a stable

ecosystem?
4.    Is this a good simulation of what happens in real ecosystems? Why or why not?
5.    Now turn the “grass?” switch to “ON” and set the wolf population to 50. Describe the size of the wolf, sheep, and grass

populations, and how they seem to relate to one another.
6.    Play with the values for grass regrowth rate, and for sheep and wolf reproduction rates. How does each of these rates affect the

stability of the system?
7.    Can you find any settings that result in a stable population, with very little oscillation?  What settings did you use
8.    Describe the interactions between these three organisms in ecological terms.  Comment on the timing of population

increases/declines for the three species.
9.    Relate the ecological concept of carrying capacity to this model.  What influences the carrying capacity for wolves?  For sheep?

What model characteristics or settings might demonstrate this concept?
Model 3: Bug Hunt Speeds
1.    How does the distribution of bug speed change as you prey on them using the “chasing” mode of hunting?  (Be specific)
2.    Try hunting with a “waiting” strategy. How did this change the distribution of speeds in your population?
3.    Run the simulation again, but set the “show colors” to “off”. Did this change the final distribution of bug speeds compared to the

rainbow setting?
4.    Explore what happens if you turn on the “wiggle” feature.  How does the bug population change?  Which hunting strategy is better?

Relate the model results to what might happen with real bugs and predators.

5.    Now explore what happens if you turn on the “flee” feature.  How does the bug population change?  Are the two hunting strategies

equally successful if the bugs can “flee”? Relate the model results to what might happen with real bugs and predators.
Model 4:  Bug Hunt Camouflage
1. Natural selection involves many small changes that accumulate over time.  Run the model several times using the default settings.  Are

your final populations the same?  If not, describe the differences.  Refer to the graphs for specific data.
2.  Compare your results with someone else’s. (Even if you are doing this at home, you can probably find someone else to play.)  What

similarities and differences do you notice between your final populations?  What factors might account for this?
2.   ENVIRONMENT specifies the background image for the model.   Run the simulation with each of the three environments (seashore,

glacier, poppyfield) while keeping the defaults for all other parameters.  How do the population color attributes differ in each scenario?

Are there differences in your ability to catch bugs?
3.  Bug Size specifies the maximum size of the bugs.  As bugs reproduce they start out extremely small and grow to the maximum size.

Change the size and run the model in one environment.  Are the bugs easier to catch when they are larger?  Does this change your final

color attributes?
4.  Can you see all the bugs?  Flash will highlight the bugs briefly.  Which bugs are “hiding” the best?  Are they in a particular

location?  A particular color?
5. With each bug you eat, a new bug is randomly chosen to reproduce one offspring. The offspring’s gene-frequency for each of the three

pigment genes may be different than the parent (as determined by the MUTATION-STEP slider). What happens when you increase this parameter?

Do the color attributes end up the same?  Does the population change more rapidly?
6. How does this model demonstrate the four steps of natural selection (variation, inheritance, selection pressure, differential

reproduction)?
Model 5: Genetic Drift T Reproduce

1. Using the default settings, run the model several times.  Did you get the same result each time?
2. Change the number of colors and run again.  How does this change the result?
3.  Change the number of turtles and run again.  How does this change the result?
4.  Genetic drift is a random process.  Use your results to explain what this means.
5.  If all of the turtles of a specific color die off, that color is eliminated from the population.   Does this occur in real

populations?
6.  The third and fourth models (Bug hunt speed and Bug hunt camouflage) demonstrate how populations change when there is selection

pressure on the population.  The last model (genetic drift) demonstrates a random evolutionary mechanism at work.  Compare natural

selection to genetic drift.
a) What type of population changes might you see?
b) How does fitness change?
c)Under what conditions would you expect genetic drift to occur?